Can FlexComm0 be set to UART_RXD and UART_TXD during ISP API at boot and also function as the ETM TRACE data pins when debugging? If NOT what are my options if I must have both?

[matthewberberic]

I am designing the HW for a new product using the LPC54606J512BD100 as the real-time MCU.  I am running into an issue that I hope you can help me with.  I must have the method for ISP API set as USART which when I read the chapter in the User Guide on the boot process explains that it must be Flexcomm Interface 0 and specifically PIO0_29 and PIO0_30 must be USART_RXD and USART_TXD, respectively.  I also have a requirement to rout out the ETM TRACE pins for firmware debug.  The problem is that the assigned TRACEDATA[1] and TRACEDATA[2] pins are the same pins as the ISP UART RXD and TXD pins.

[victorjimenez]

Hello Matthew Berberich,

When you enter to ISP mode the MCU loads automatically the configurations for the pins P0_29 and P0_30 to work as UART_RX and UART_TX. Once you exit the ISP mode, in your application you can configure these pins to work with the function 5 that corresponds to TRACEDATA[2] and TRACEDATA[1]. If you enter again to the ISP mode the MCU will configure again these pins to work as a UART ISP automatically, but when you make a reset to exit ISP mode your application will load the configuration to work as the ETM TRACE pins again.

Hope it helps!

Victor.

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[matthewberberic]

I have NOT found an answer to this question, but I have a new requirement which is to require the TRACE debug and USART communications to be active simultaneously.  This now makes this question no longer valid.  There was no feedback to this point, so just wanted to say I no longer need an answer here.  My solution is to move to the 208 pin LQFP package which allows for more flexibility to select TRACE pins to be different from the dedicated ISP API USART interface pins.  This solution is NOT ideal as it adds cost and development time in re-doing pin configuration on the MCU, but that's the only solution I found to this problem after adding this additional constraint.